As well known, some binaural sound reproducing systems comprise two microphones respectively mounted on right and left simulated ears of a dummy head. It has been generally believed that the sizes and shapes of a dummy head as well as simulated ears have to be designed as close as those of actual human head and ears so as to record aural signals by microphones disposed in the simulated ears under almost the same conditions as a live person listens to the aural signals. However, the output signal of the microphone of a binaural recording system using simulated ears having almost the same shape as those of human being, i.e. the simulated ears have undulations on the front surfaces thereof, has a dip in its amplitude frequency characteristic curve in a range of approximately 8 KHz to 14 kHz. Because of this dip the response of the microphone at high frequencies is deteriorated so that hi-fi recording is disturbed, while the clarity of acoustic image is reduced. For this reason, the quality sounds reproduced by the conventional binaural sound reproducing system is apparently lower than that obtained by a regular stereophonic sound reproduction system. Although it seems to be possible to compensate for this dip by means of a suitable equalizer, it is quite impossible to employ such an equalizer since adoption of an equalizer introduces undesirably deteriorated signal-to-noise ratio.